Suppose the pilot pressure range is from 3 to 15 psig for the illustrated pneumatically-operated diaphragm-actuated control valve. Assuming the control valve is trimmed for a linear response and the travel position indicator is calibrated in percentage, what would the approximate valve position with a 9 psig pilot pressure? GS-0051

Question

Accepted Answer

Option C: 50% open. For a standard 3-15 psig control range, the span is 12 psig. A 9 psig signal represents the midpoint of this range (9 - 3 = 6 psig; 6 / 12 = 0.5). Therefore, a linear valve will be at 50% of its total travel at this specific pilot pressure.